The present invention relates to an apparatus for collecting chemical samples, and more specifically, to an apparatus that is capable of collecting particles or molecules adhered to a surface.
Many situations arise requiring the capability to detect the presence or absence of a chemical on a surface. One important example is the detection of toxic and hazardous substances in the environment, such as explosives and chemical agents. Searching for toxic or hazardous substances involves monitoring a variety of different surfaces and checking for the presence of particular chemicals.
In general, the process of detecting a chemical comprises three main steps: acquiring the sample, conditioning the sample, and employing a chemical detector to detect, identify and quantify the specific chemical of interest, herein referred to as the target analyte or target. Sample acquisition comprises the removal of the target analyte from a surface or host matrix to which it may be attached. Sample conditioning comprises the preparation, conditioning, or processing of the sample prior to its introduction to a chemical detector. Detecting the target analyte with the chemical detector involves determining the presence or absence of the target chemical on or in the chemical detector.
Although chemical detection is conventionally viewed as being defined by the lower limit of the detection ability of the chemical detector, the performance of the chemical detector alone does not accurately characterize the ability of the entire system to detect the presence of a specific chemical. In many cases, performance is significantly affected by sample acquisition and conditioning.
Often, it is difficult to acquire a chemical sample when the chemical is adhered to a surface, particularly if the vapor pressure of the chemical is low, or if the temperature is low. Under these circumstances, only a small amount of molecules may be in the gas phase and available for collection. Additionally, the surface of the chemical may become crusted-over with time, which further reduces the quantity of vapors in the gas phase available for detection.
Accordingly, a need exists for an improved system for collecting chemical samples, particularly when the chemical is adhered to a surface.